Who wants to help me search?

I would love to find something for Madi that she can use out back, around the block, etc... to move herself around.  Walks have been a challenge because Madi doesn't want to be in a carrier any more.  She wants to be down, doing what her brother is doing, and who can blame her??  The problem is she is not even 18 months old yet, so she needs something designed for younger children.  I found something that looks very cool, but WOW, I cannot believe how much they want for it!  Some companies really take advantage of the lack of options out there for children with special needs, and it is terrible.  This is what I found...

It has a handle so you can push it if you need to, but the child is also able to move the wheels themselves with their hands/arms to get around.  I think Madi would love somthing like that, but obviously we need to find a cheaper option.  Our Amazon money is starting to add up, but not quite that much ;).  If anyone either knows where to get one used, or something else that might work but costs less, PLEASE let me know! 

On the plus side, someone from church has a intramuscular stimulator that might work for us, so we can use that and not need to purchase one, if it is in the frequency ranges that we need.  That would be very awesome if that works out!